1958 Chevy Corvette C1 - The Fuel Monty

Part 2: We finish off our C1 fuel-system update with a dual-quad intake setup from Summit Racing.

In our March issue, we covered the process of swapping our '58 project car's crud-loaded stock gas tank for a fresh replacement unit from Corvette Central. While that operation alone would likely have vanquished the severe fuel-delivery problems that landed the Vette in the shop to begin with, we decided to press on to the engine compartment this month and install a modern high- performance carb-and-intake combo.

As we noted previously, the C1's original 283 had long since been jettisoned in favor of a high-performance 406 SBC topped with a Holley four-barrel and an Edelbrock Performer intake manifold. While this pairing remained fully operational, the car's new owner was keen to install something with a little more performance potential and visual pizzazz. Inspiration ultimately struck while he was thumbing through some vintage drag-racing photography, and a plan was hatched: We would assemble a full dual-quad setup inspired by the early competition Vettes of the mid-to-late '50s.

When we shared this approach with our man at Summit Racing Equipment catalog, he suggested that we remove any potentially ruinous guesswork from the equation by installing Edelbrock's Performer RPM Dual Quad Air-Gap Kit (PN EDL-20254, $1,299.95). This all-encompassing package includes an RPM Dual Quad Air-Gap intake, two 500-cfm Thunder Series AVS carburetors, a throttle linkage, fuel lines, and intake-manifold gaskets. It's available in Edelbrock's chrome-like EnduraShine coating (which we selected) as well as in a standard finish treatment.

As you'll see in the accompanying photos, the project hit a temporary snag when a preliminary test fit revealed the Performer RPM setup to be too tall to fit under the C1's factory hood. Since the car's owner was disinclined to install a bulged aftermarket bonnet for clearance, we scoured the Summit catalog for a suitable intake alternative.

We eventually settled on an Edelbrock C-26 Dual Quad unit (PN 54254, $379.95), a proven design that, while less aggressively configured than the Performer RPM piece, should produce excellent performance and driveability atop our C1's moderately modded stroker engine. Though it was conceived back in the '60s, the low-profile C-26 is currently available to fit both standard SBC heads (like ours) and the later-model Vortec configuration.

While this is a fairly straightforward job, our dual-quad setup does require a few configuration-specific installation and setup procedures. We'll cover those—along with the rest of the job—in the accompanying photos.

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1958 Chevy Corvette C1 - The Fuel Monty

1. When it came time to update the top end of our '58's stoker small-block, we turned to the parts pros at Summit Racing Equipment for advice. Our Summit contact recommended an Edelbrock kit based on the company's Performer RPM Dual Quad Air-Gap intake manifold, shown here.

2. One of the chief advantages of the Air-Gap manifold stems from the design element that gives it its name. Maintaining an open space between the intake’s runners and base helps keep the air charge cool as it enters the engine.

3. An all-encompassing package, the Performer RPM Dual Quad Air-Gap Kit also includes a pair of these 500-cfm Thunder Series carbs, along with gaskets, fuel lines, and a linkage.

4. Even in mocked-up form, our new intake setup is a real head-turner. Edelbrock’s optional EnduraShine finish provides the look of lustrous chrome, without the maintenance hassles.

5. The ’58’s pre-swap top end, in situ. Note that the Edelbrock Performer intake and Holley 750-cfm carb remained fully functional, and the decision to replace them was based more on desire than necessity.

6. After removing the air cleaner, AntiVenom’s Greg Lovell begins the swap by pulling the distributor.

7. Next to go is the carburetor…

8. …followed by the intake manifold.

9. With the Performer RPM intake laid in place, it was becoming evident that hood clearance was going to be a problem. Still, we pressed on and mocked up the full top-end combo, just in case.

10. The hood had been removed earlier, to ease the process of installing the new top end. No matter: Laying a bar across the engine-bay opening provided a rough approximation of the height mismatch.

11. This view across the fender tops verified what we already knew. Since the car’s owner was unwilling to install even a subtly bulged hood, we initiated our backup plan.

12. This comparison shot shows the Performer RPM intake (left) alongside Edelbrock’s venerable C-26 dual-quad manifold. While the lower-profile configuration of the C-26 will likely sacrifice some top-end horsepower, it should still represent an improvement over the old Performer single-quad unit.

13. After scraping the old gasket material from the heads (remember to block off the ports first!), Lovell installs the new intake-manifold gaskets.

14. Next up is the intake itself, which is Permatex Ultra Gray RTV.

14a. Followed up by the two gaskets and eight studs for the carburetors.

15. Before installing the carbs, Lovell blocks off the unneeded vacuum ports. In other, more modern applications, these would be used to feed vacuum to the power assists, EGR valve, and other accessories.

16. With that done, it’s simply a matter of bolting the carbs to the intake—and the major portion of this install is complete.

17. The next steps involve hooking up the throttle linkages. Edelbrock includes one linkage with the kit, but you’ll need to fabricate a second one to fit your specific application.

18. Once the linkages are in place, test them by slowly pulling back on the rear linkage to simulate the gas pedal traveling through its full range of motion. At part throttle, only the front carb should engage, as shown.

19. Then, as the throttle is more fully depressed, the blades on the second carb should swing open.

20. Edelbrock also includes this lockout collar, which allows you to fully remove the second carb from the equation if you so desire. This might be useful for increasing fuel mileage during a long, relaxed cruise.

21. It seemed a shame to reuse the Vette’s crusty, old valve covers with our gleaming, new intake setup, so we contacted Corvette Central for suitable replacement units. CC sent us a set of its polished, sand-cast-aluminum covers (PN 301239, $429), complete with vintage-style “Corvette” script. As you can see here, the combo is a real stunner.

22. The Edelbrock kit includes this braided-steel fuel line for attaching the two carbs, but you’ll need to source the rest of the lines on your own. While conventional braided or rubber hose will be sufficient for most, this Vette’s owner wanted to go the extra mile by using polished hard lines.

23. Fortunately, Lovell is experienced with this sort of thing and leapt at the challenge.

23a. After shaping the lines with a tubing bender, he flared their ends to the necessary diameters with a 37-degree flaring tool.

24. A polishing wheel produces the requisite shine.

24a. Next, the line is ready to be bolted in place.

25. At this point, all that remains is the task of wiring up the electric choke. The red wire should be attached to a keyed ignition source; the black, to ground.

26. And with that, you’re done. Quite a transformation, no? We’ve got quite a lot more planned for this ’58 in the months ahead, so stay tuned. vette

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